Brass vs SS

[dunney]

Hi folks. I need some advice please
I'm in the process of upgrading to a 3V setup using 50l kegs for HLT, kettle and possibly mash tun.
I've purchased BRASS ball valve and fittings because of low price
What are pros and cons of brass vs SS (other than price difference)

 

[Ducatiboy stu]

Germicidal and antimicrobial applications
Main article: Antimicrobial copper-alloy touch surfaces
See also: Antimicrobial properties of copper and Copper alloys in aquaculture
The copper in brass makes brass germicidal. Depending upon the type and concentration of pathogens and the medium they are in, brass kills these microorganisms within a few minutes to hours of contact.[16][17][18]
The bactericidal properties of brass have been observed for centuries and were confirmed in the laboratory in 1983.[19] Subsequent experiments by research groups around the world reconfirmed the antimicrobial efficacy of brass, as well as copper and other copper alloys (see Antimicrobial copper-alloy touch surfaces).[16][17][18] Extensive structural membrane damage to bacteria was noted after being exposed to copper.

 

[Ducatiboy stu]

Always wondered why they used brass taps on water tanks.

 

[Ducatiboy stu]

Interesting

http://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper

 

[spog]

Germicidal and antimicrobial applications
Main article: Antimicrobial copper-alloy touch surfaces
See also: Antimicrobial properties of copper and Copper alloys in aquaculture
The copper in brass makes brass germicidal. Depending upon the type and concentration of pathogens and the medium they are in, brass kills these microorganisms within a few minutes to hours of contact.[16][17][18]
The bactericidal properties of brass have been observed for centuries and were confirmed in the laboratory in 1983.[19] Subsequent experiments by research groups around the world reconfirmed the antimicrobial efficacy of brass, as well as copper and other copper alloys (see Antimicrobial copper-alloy touch surfaces).[16][17][18] Extensive structural membrane damage to bacteria was noted after being exposed to copper.

And that about covers it,interesting all the same.
Cheers...spog..

 

[technobabble66]

So why aren't we all using brass fittings?

 

[technobabble66]

I should probably point out I'm actually keen to know. I'm looking at buying a brass float valve for my MLT so I'm keen to know if there's a good reason to avoid brass over SS.

 

[pk.sax]

Brass also reacts with caustic brewery cleaners.

The brass available for cheap 'could' have lead content, not really good for us. This can be pickled out but harsher cleaners can strip the protective layers and expose more lead.

So, ss turns out easier to manage.

 

[sponge]

And SS really isn't that much more expensive. Worth the extra $$ IMO..

 

[NewtownClown]

Brass also reacts with caustic brewery cleaners.

The brass available for cheap 'could' have lead content, not really good for us. This can be pickled out but harsher cleaners can strip the protective layers and expose more lead.

So, ss turns out easier to manage.

Actually, all brass contains lead. It is added to make the alloy more machinable. The ratio varies but it is generally <3% for plumbing applications. Not enough to really be a health concern but it still weighs on my mind.

Besides easier manageability of going all SS, the issue of galvanic corrosion is avoided when using like metals in an acidic environment.

 

[technobabble66]

Brass also reacts with caustic brewery cleaners.
...

I only use a sodium perc & sodium metasilicate combo, and starsan. Are they ok on brass or too harsh?
Fwiw, my MLT is plastic, so the electrolysis thing shouldn't be important for me, though it's def noted for other applications.

(Apologies for railroading OP)

 

[technobabble66]

...
So, ss turns out much, much shinier.

FIFY :lol:

 

[DJ_L3ThAL]

I recall john palmed discussing it and if the brass is machined it exposes the lead to a greater extent than straight cast pieces. In our application I think the achieved surfaces are in contact with the beer much more than water tanks where the tap ports are cast, although the valve seat is probably machined? The water parts for plumbing applications have most likely been pickled then?

At $25 for a 3 piece 304SS ball valve you can't really go too wrong, plus as mentioned SHINY!!!

 

[QldKev]

Look at a brass fitting after 2 years of service in a boil, yuk. s/s will look like new. And the idea of the lead in it at the acid levels we reach and the temperatures, stainless is the choice for all my new parts. But for the record I still have brass parts in my 1V as I grabbed what ever bits n pieces where in the workshop at the time.

 

[Feldon]

I haven't heard that Palmer comment about there being a lot of lead exposed if the fitting is machined. So happy to be corrected.

I put my thoughts on this matter in a post last year. The main point being that the lead is not part of the copper/zinc alloy (which is what brass is). At the atomic level lead doesn't fit in the lattice structure of the repeating copper and zinc atoms. When a melt of brass with added lead is cast, as it cools almost all of the lead finds its way to the surface (ie. it is squeezed out as the copper and zinc atoms start arranging themselves in an ordered matrix which uses up the maximum amount of space, leaving little or no room for the lead).

So the lead oozes to the surface of the casting, which it can do easily because as the fitting cools there is a point where the brass (copper/zinc) becomes solid while the lead is still liquid (it having a much lower melting point than the other two metals). If any lead did not make it to the surface it would exist within the casting as small discrete 'globs' (ie. its not part of the alloy).

My understanding is that the "black specs" on brass fittings is lead. You don't see it where the fitting has been machined (eg. to form threads). Machined surfaces show that beautiful buttery golden colour.

Brass is an alloy of copper and zinc. In manufacture lead is added to molten brass because it melts at a lower temp than the copper and zinc.

When the molten metal mixture is injected into the die (or mold) to form a cast of the fitting, the copper and zinc solidify first and their atoms arrange themselves in a repeating matrix with no space between the atoms for the lead, which is still in a liquid state. So the lead is forced to the outside of the casting. This where it fufils the reason why it was added in the first place. It acts as a mold release agent ensuring that the fitting does not stick to the tool steel of the die. The casting is easily ejected as the lead finally cools and soldifies on the external surface of the casting, leaving a black discolouration. (spray on mold release compounds are used too and may contribute to the discolouration)

What this means in brewing is that exposing your hot wort to machined surfaces of a brass fitting (where the lead contamination has been cut or drilled away) is probably OK. But exposing wort to extenal blackened surfaces (eg. a brass hose barb on a false bottom) risks getting the lead on the surface into the wort.

It is often said that there is only a tiny percentage of lead used in the brass casting, but be aware that this small amount can end up concentrated on the external surfaces. As has been said, Palmer's book How to Brew (free online) details how to remove the lead from the surface by a pickling process.

 

[sponge]

At $25 for a 3 piece 304SS ball valve you can't really go too wrong, plus as mentioned SHINY!!!

Or a 3 piece 316SS for $14 delivered.

 

[Adr_0]

Anybody know of a good outlet for SS tube fittings?

 

[DJ_L3ThAL]

I haven't heard that Palmer comment about there being a lot of lead exposed if the fitting is machined. So happy to be corrected.

I put my thoughts on this matter in a post last year. The main point being that the lead is not part of the copper/zinc alloy (which is what brass is). At the atomic level lead doesn't fit in the lattice structure of the repeating copper and zinc atoms. When a melt of brass with added lead is cast, as it cools almost all of the lead finds its way to the surface (ie. it is squeezed out as the copper and zinc atoms start arranging themselves in an ordered matrix which uses up the maximum amount of space, leaving little or no room for the lead).

So the lead oozes to the surface of the casting, which it can do easily because as the fitting cools there is a point where the brass (copper/zinc) becomes solid while the lead is still liquid (it having a much lower melting point than the other two metals). If any lead did not make it to the surface it would exist within the casting as small discrete 'globs' (ie. its not part of the alloy).

Youre right, I got it backwards, the machined parts have the lead which rises to the surface taken off but the cast parts have lead that would need pickling to address. Apologies for the confusion! Thanks for the info.

FWIW the discussion was on the brew strong podcast Q&A on Mettalurgy here: http://www.thebrewingnetwork.com/shows/1030 hope it is helpful. It got me to remove my 2 piece brass valve and get a 3piece 304ss valve!

 

[DJ_L3ThAL]

Anybody know of a good outlet for SS tube fittings?

Fullpint.com.au no affil yada yada

 

[pk.sax]

@tb66, yes - oxidising agents are caustic (or more correctly - alkaline or basic reagants). Some more than others. Using acidic cleaners is fine.

@ sponge, just a word of caution on that cheapy 3 piece ss valve, it is really really cheap quality and he actually sent 304 ss. Quite a bit of rust from machining swarf or whatever. Had to clean up a bit. Plastic seals in the thing are ordinary at best. To his credit he refunded the amount paid.